More than 1.1 billion people in the world lack access to clean drinking water. Many factors account for this shortage, such as contaminants from industry and agriculture, naturally occurring elements, and climate. Often it is simply geography. Islands are surrounded by water, but unless they have natural springs, they may lack access to potable water.
That is what’s happening in Italy’s Aeolian islands, a volcanic archipelago that lies about 40km north of Sicily. But this area has a solution to its water shortage. There, a new desalination plant uses an efficient reverse osmosis system to save 36,000 litres of diesel a day in peak season over the previous evaporation system. The 79 tons of CO2 emissions saved from this every day is equivalent to that generated from flying round-trip from New York to London 42 times.
A growing island, a growing problem
Lipari, the largest island and main entrance point for tourists to the Aeolian islands, has a permanent population of about 11,000 and no source of fresh water. For years, water was shipped from Sicily and Naples to satisfy the needs of locals and visitors. At a reported cost of more than €10 per metric cube of shipped water, this solution was feasible, yet costly, during winter months.
In the summer, however, the island’s population and water needs grow dramatically. Official figures cite 200,000 tourists throughout the season. Lipari’s mayor, Marco Giorgianni, suggests twice as many may arrive over the August peak. It is during these times that the scarcity of potable water on Lipari becomes increasingly pressing.
A plant built in 1998 used an evaporation system and high-pressure pumps to produce enough water to satisfy locals during the winter months. But the islands needed more drinking water at greater energy savings than the system could provide.
Two-season solution
The area needed something new, and to meet this demand Italian firm Sled Costruzioni Generali S.pA. created a more efficient plant using desalination and reverse osmosis.
Elena Bonadei, the project’s manager, is a process engineer for water treatment plants, and has worked on more than 30 all over the world. She and her team planned the Lipari plant in a series of stages.
“The plant uses a skid-mounted reverse osmosis (RO) system to convert seawater into potable water,” she says. “The reverse osmosis process removes salt and other substances from water molecules by applying pressure to the solution when it is on one side of a semipermeable membrane. Undesirable contaminants like salt are retained on the pressurised side of the membrane while the purified water passes to the other side.”
Drinking in the benefits
Not only is the system capable of generating almost three times more potable water than the old evaporating system, but it does so more efficiently and economically, lowering the energy consumption to less than a third. It incorporates an energy recovery device that recovers up to 96% on the brine side.
Moreover, the total flow rate of the desalination plant is 450 cubic metres per hour and each of the three sections can be managed independently. All three operate together during peak season, while one section alone can handle the island’s needs during winter months.
Read more and see a video about the Grundfos reverse osmosis solution on Lipari here.
Copy on this page is provided by Grundfos, sponsor of the water hub
